BACKGROUND: Little is known about the longitudinal course of health-related quality of life (HRQoL) in patients with Hodgkin's lymphoma during their post-treatment follow-up and re-adaptation to normal life. We report on the HRQoL of patients treated in the randomised H8 trial of the European Organisation for Research and Treatment of Cancer (EORTC) Lymphoma Group and the Groupe d'Etudes des Lymphomes de l'Adulte (GELA). We aimed to assess HRQoL and fatigue following treatment, to analyse relations with treatment, and to identify factors that predict persistent fatigue. METHODS: Patients received HRQoL questionnaires at the end of primary therapy and during follow-up. The EORTC QLQ-C30 was used to assess HRQoL, and the Multidimensional Fatigue Inventory (MFI-20) was used to assess fatigue. Changes of mean HRQoL scores over time were analysed with mixed models. Multiple polytomic nominal logistic regression was done to identify independent baseline predictors of fatigue within MFI-20 dimensions. Analyses were done on an intention-to-treat basis. This study is registered with www.ClinicalTrials.gov, number NCT00379041. FINDINGS: 2666 assessments from 935 patients were analysed. Mean follow-up was 90 months (range 52-118). Age affected all functioning and symptom scores except emotional functioning, with younger age associated with higher functioning and lower severity of symptoms; improvement with time showed similar patterns between age groups. Women reported lower HRQoL and higher symptom scores than did men. Overall, 3.2% (14/439 for role functioning) to 9.7% (43/442 for social functioning) and 5.8% (29/498 for reduced motivation) to 9.9% (49/498 for general fatigue) of patients reported impairments of 10 points or more (on a 0-100 scale) in QLQ-C30 and MFI-20 scores, respectively, independent of age and sex. Emotional domains were more affected than physical ones. There was no relation between HRQoL outcome and type of treatment. Fatigue (MFI-20 scores) at the end of treatment was the only predictive variable for persistent fatigue, with odds ratios varying from 2.58 (95% CI 1.00-6.67) to 41.51 (12.02-143.33; p</=0.0001). Sensitivity analyses adjusting for missing data were much the same as the main results. INTERPRETATION: HRQoL data after treatment for early-stage Hodgkin's lymphoma show that patients experience strain and limitations in all subdomains apart from cognitive functioning (QLQ-C30), and also have reduced motivation (MFI-20). Differences in HRQoL improvement with time were linked to age and sex, but not type of treatment. Fatigue status at the end of treatment seems to predict subsequent HRQoL. FUNDING: French Ministry of Health, Programme Hospitalier de Recherche Clinique 1994, and French National League Against Cancer.